In a conventional process for preparing a multi-layer superconductor article, a reactor (e.g., a tube furnace) includes a housing having an upper wall with passages (e.g., slots or nozzles) that are in fluid communication with gas mixture sources (e.g., oxygen, water, and one or more inert gases (e.g., nitrogen, argon, helium, krypton, xenon). A substrate, which is wound around reels, moves through reactor in a predetermined direction.
As a substrate enters the reactor, it passes through a various regions within the reactor, during which time the gas mixture is directed downward, toward substrate. A film containing a precursor (e.g., a superconductor precursor film containing barium fluoride and/or additional materials, such as CuO and/or Y2O3) is present on the surface of substrate, moving through the regions of the reactor. The precursor is exposed to the gas mixture, reacting therewith. Spent reaction gas is drawn-off by a pump that directs the spent gas through a through a porous material positioned adjacent the passages (the slots or nozzles) in the upper wall.
In the conventional system using the above process, fresh and used reaction gases are mixed without control. This, in turn, leads to impairment of quality of the HTSC layer and/or long retention times of the strip in the furnace. Thus, it would be desirable to develop an HTSC formation method that controlled to level of mixing between the fresh and used reaction gases.